Drifting sand

A piece of Mars: Dark sand has been blown into the scene from the upper right. It has piled up against older, brighter dunes that may now be inactive. The sand drifts on and on, piling up where the wind weakens and carving out rock where the wind is strong. And that is geology on

Mars’ giant amphitheater

A piece of Mars: Sandwiched between hills, a huge stepped amphitheater has been carved out of the rock by the wind. The scene is 770×577 m across, with each giant step about 20 m wide. Just imagine a huge concert taking place down in the bottom of this monstrous gap (except the acoustics on Mars

Dunes being buried

A piece of Mars: Most dunes on Mars are the freshest, youngest features around. Not so here. The bright dunes near the bottom here are slowly being buried by debris coming down from the gullies on the slope, coming from the upper left. (HiRISE ESP_029483_1470, NASA/JPL/University of Arizona).

Dunes. Just dunes.

A piece of Mars: These large dunes are located in Kaiser crater, a big crater in the southern midlatitudes. The scene is 789×592 m across. Imagine standing on one of these monsters, and seeing nothing but pristine ripples criscrossing all over the place. (HiRISE ESP_029500_1330, NASA/JPL/University of Arizona)